The need for air control systems first became apparent in the 16th century with the advent of chimneys in Europe. Despite improvements since then, most chimneys still operate on a natural draft system. A natural draft chimney operates by force of gravity. That is, the hot flue gases in the chimney are lighter than the surrounding ambient air. Being lighter, flue gases are displaced by cooler, heavier air and rise buoyantly through the chimney flue creating a natural draft.
This natural drafting is affected by a host of environmental factors. Ambient air temperature and atmospheric pressure affect the density of the ambient air mass. If the density of the ambient air mass is reduced, the efficiency of the natural drafting is reduced as well. For example, wind can either increase draft by blowing across the intake portion of a natural drafting system creating a venturi effect, or reduce draft if turbulent. In addition, wind can cause a back draft, a reverse flow through a system. In the case of a chimney, this can cause flue gases to be vented within a building.
Over the years, systems have been developed where appliances are designed to operate in modular or modulated fashion. Boilers, heaters, water heaters, and other appliances operate in groups. Each unit may fire or power up at different times in response to specific demands. As a result of this modular configuration, the demand upon the pressure, temperature, and the like, within the enclosed building can vary greatly depending on the operation of these appliances.
These factors create the potential for insufficient draft and overdraft which may cause undesirable, and even unsafe conditions within the enclosed air system. In addition, failure to control the quality of air within an enclosed environment, or the flues connected to the appliances for exhausting air, may drastically impede the efficiency and general operation of the appliances since an appliance or group of appliances require specific air flow rates for optimal performance.
With regard to draft systems, power venting systems have increased in popularity. The conventional power draft systems fall into two basic classes. The traditional mechanical draft system is a so-called constant volume system in which a fan provides a constant volume gas flow through a flue to carry exhaust gases to the exterior. Likewise, the mechanical draft system could also be set up to provide an intake air flow for bringing air into an enclosed environment or air system. This constant flow of air thorough an air system is inefficient and costly. Three to five thousand cubic feet per minute of air may be expelled by these systems causing loss of heat in the winter and loss of cooled air in the summer. In the case of intake flows, the mechanically drawn air brought into an air system could provide an undesirable pressure within the system. In addition, this inflexible flow of air in or out of the air system can again impede the efficiency and general operation of any appliances.
In recent years, power venting systems have been implemented in HVAC, kitchen, and other systems to deal with the inherent drawbacks of a mechanical draft system. Namely, controller devices have been advanced which connect to intake and outtake fans for controlling air system characteristics in a single system. Generally, these systems are most often utilized in detecting and controlling the pressure characteristic within a vent flue. Two sensors are placed within the venting system to sense pressure changes. These sensors are in communication with one electronic controller for processing data and controlling input and output devices, such as the sensors and fan. Typically, these two switch sensors are used with one sensor defining the low pressure point and the other defining the high pressure point. Each pressure setting is defined by inputted parameters. These two pressure points define a window of acceptable pressure within the venting flue. If the pressure in the flue falls outside this window, the relevant sensor is triggered and provides a closed circuit for sending a signal to power the fan up or down, depending on which sensor is triggered. In such a system, the fan adjusts the pressure by fully powering up or down, or in the alternative, by switching to predetermined limited speeds such as high, medium, low, or some other variation. While an improvement over more traditional mechanical draft systems, this method of adjustment is costly and inefficient, and fails to make the precise system-wide adjustments needed to maintain a truly “continuous” pressure system. While such systems may be referred to as “constant” pressure systems, such a designation is not a true characterization of their operation.
The innate drawback of such an “on-off” air control system is that it is incapable of providing and maintaining a constant pressure within the system. The pressure window may be so large as to permit a great range of pressure deviation before any adjustments are made by the turning on of a fan. Similarly, if the pressure window is made small in an attempt to maintain pressure, the fan is frequently turned on and off to adjust for fluctuations in pressure. On-off switches and non-variable fan motors may continuously jump through pressure levels in an attempt to maintain pressure, but they are incapable of keeping pressure at precise levels, especially when an air system is dynamically effected by the demands of multiple appliances and changing environmental factors such as wind.
Even those systems that have attempted to implement a single sensor to measure and maintain a characteristic such as pressure do so using these “on-off” techniques, and inevitably jump the fan speed to predetermined and limited levels. In addition, conventional systems fail to maximize the efficiency and effectiveness, and reduce the cost, associated with controlling their systems since they implement an independent controller for each system, and fail to arm the controllers they do use with effective appliance interfacing and adaptive technology.
Those conventional systems attempting to monitor and maintain an environmental characteristic, unfortunately, do assign one controller to each air control system. For example, one controller would receive sensor input and provide control over a venting system, and a separate controller would be assigned to a combustion intake system. Consequently, repetitive circuitry and control structures are required for each system, even when numerous air systems (i.e., venting, combustion, and heating) are contained within one building. This presents a significant cost problem, as well as a training and standardization problem. The cost problem is significant at the production level, and at the purchasing level. A purchaser would obviously prefer not to expend monies on a controller for each individual air control system contained within a particular enclosed environment. In addition, the training and standardization problem likely increases over time. As time passes, it is quite possible that vastly different controllers will be purchased and implemented for the different air control systems within one enclosed environment. Each controller will operate differently, varying in operating parameters, inputting methods, and other functions. Training, usage, and maintenance costs will also increase with the employment of an individual controller at each air control system. The standardization benefits and cost savings would be substantial if only one controller was used to monitor and control a plurality of air control systems.
In addition, the conventional wisdom is to collectively deal with appliances within an air control system. Regardless of the individual effect of any one appliance on the system, the appliances are addressed as a group. For instance, if one appliance fires up and causes a significant pressure change in the system, and the controller is unable to control the pressure through an exhaust fan adjustment, an entire block or group of appliances will be shut down until the problem can be addressed. In addition, this restrictive view of appliance groups does not permit the system to retain historical data representative of each individual appliance tied into the overall air control system. If historical data could be stored, modified, and utilized by the controller for each appliance, efficiency and system performance could be significantly increased.
For example, in the previously given scenario, it was merely the firing up of the last appliance that caused the system to exceed the bounds of the acceptable pressure parameters. Ideally, an intelligent air control system, and specifically the controller, would be operably interfaced with all of the appliances individually within the system, such that the last fired appliance would be the only appliance shut down to keep the system within the acceptable parameters.
Another application of an intelligent controller centers around the ability to bypass time consuming and costly operational steps. For the sake of illustration, it would be beneficial for a controller to keep track of what system adjustments were needed under specific pressure requirements, taking into account the demands of the appliances, wind, and other factors. For example, instead of systematically adjusting fan speed to obtain a desired pressure based on a system demand, it would be more efficient to immediately adjust the speed of the fan to a specific acceptable level based on known past historical data for an identical or similar demand. This historical data could be stored and evaluated for a nearly endless array of appliance combinations, pressure requirements, and environmental factors. Such a controller would be able to learn from past operations and adapt in a manner permitting more efficient operation any time a specific situation arises in the future. Along these same lines, it would be beneficial if this valuable data regarding system operations, appliance functioning, system demand, and the like could be made available through electronic communication to other independent systems such as those used for building and facility management.
As a result of each of these existing deficiencies, there is a need for an air control system which is capable of maintaining an environmental characteristic, such as pressure, at a constant rate within an enclosed environment, even when the enclosed environment is periodically subject to system-altering internal factors, such as the powering up of appliances, and external factors, such as wind gusts entering the system. Additionally, there is a need for one centralized system controller equipped to monitor and control two or more systems in their corresponding enclosed environments, doing so in a manner that reduces costs and increases efficiency and standardization. This system controller should be able to individually interface with each appliance within the air control system such that system-wide needs can be more clearly understood, enabling the controller to make more accurately focused adjustments to meet those needs. Moreover, there is a need for this controller to be equipped with adaptive technology, enabling it to again increase efficiency, and to better enable it to make informed decisions to control and maintain an environmental characteristic parameter within each attached system.